Clinical literature suggests that intermittent cycles of repeated cocaine dosing i.e., binges, followed by abrupt cessation of cocaine use are associated with distinct pattern of withdrawal symptoms and signs 1)can change in affect,sleep & reports of withdrawal symptoms following termination of cocaine binge be related to the magnitude and duration of the binge? 2)what are the differences in response to cocaine abstinence following binges with smoked cocaine compared to intravenous (i.v.) cocaine?